From The Ergoweb® Learning Center

Study: Behavioral Based Intervention Inneffective at Reducing Whole Body Vibration

A whole body vibration (WBV) safety program mostly comprised of administrative controls — changes in work methods such as route selection, driving speed, and driving style — was found to have little impact on median exposure to WBV in a European prospective cohort study involving 126 drivers and 9 employers over a 7 month period.  Although over half of the drivers (55%) who were in the intervention group reduced their exposure to WBV, a sizable proportion (38%) had an increase while some stayed the same (7%).  Drivers in the control group (those that did not receive the intervention) showed no difference in median WBV exposure over the course of the study.

A greater portion of drivers in the intervention group (23%) reduced their WBV exposure to below the WBV European Directive Action Limit compared to the control group drivers (12%).

When evaluating intervention group compliance, the study found that only 19 out of 65 drivers followed at least half of the recommended work changes.  The primary explanation drivers gave for their insubordination was high work pressure – too much work to drive slower, take more breaks, or change driving style.  Also, drivers reported a lack in belief that work changes would lower their WBV exposure.

The work environment source of whole body vibration for drivers in this study came from wheeled loaders, lawn mowing machines, bulldozers, tractors, excavators, lorries, dumpers, steamrollers, boats, mobile cranes, and asphalt machines. 

The Bottom Line – How This Applies To Ergonomists
This study shows that getting the job done is a focal concern of workers and has to be appreciated by the ergonomist when proposing solutions to workplace hazards. 

Following behavioral theory, the authors felt that if the knowledge/awareness of the potential outcomes related to WBV exposure was increased and if company policy was altered, worker behavior would change to lower WBV exposure.  Although there were some signs of favorable outcomes in this study, poor worker compliance showed job completion trumped health concerns. 

Most ergonomists have experienced and recognize the potential of this type of behavior based program failure.

Other Key Study Points
When there was program compliance, there was a reduction in driver WBV exposure.

For employers in this study, no significant increases were found in WBV knowledge or company policy when comparing the intervention group to the control group.

At the end of the study, the control group answered questions relative to WBV as well as the intervention group.

Study Method
The study population was a group of 126 drivers and nine employers.  All drivers were exposed to whole body vibration above the European Directive Action Limit (A[8] ≥ 0.5m/s2). 

Research Design
The study population was randomly divided into two groups: an intervention cohort and a “care as usual” cohort.  The two groups were comparable in age, height, weight and driving experience.

Those within the intervention group received:

  1. An individual health surveillance performed by an occupational health physician which produced two to five recommendations (mostly behavioral suggestions with an occasional engineering control) to reduce exposure to whole body vibration.  A follow up telephone call was made after one month between the subject and the study’s principal investigator.
  2. An European Directive brochure containing information on whole body vibration.
  3. A training.
  4. Findings of whole body vibration measurements.

Those within the “care as usual” group received (at a minimum):

  1. A European Directive brochure containing information on whole body vibration.
  2. Findings of whole body vibration measurements.

The study design did not blind the subjects or researchers as to who did and did not receive the intervention.

Driver Outcome Measurements
At both baseline and seven months later, WBV measurements for each driver were taken and the knowledge, attitude, and behavior toward WBV was evaluated.  Also, at the seven benchmark, information was gathered through a questionnaire relative to the intention to change behavior, intervention group compliance, and intervention program problems.  

Employer Outcome Measurements
At both baseline and seven months later, awareness of WBV concerns and company policy towards WBV was evaluated.  Problems relative to the interventions were assessed at the seven month point.

This complete paper can be acquired at:

Article Title: Effectiveness of an Occupational Health Intervention Program to Reduce Whole Body Vibration Exposure: An Evaluation Study With a Controlled Pretest-Post-test Design

Publication: American Journal of Industrial Medicine, 52:943-952, 2009

Authors: I J H Tiemessen, C T J Hulshof, and M H W Frings-Dresen

This article originally appeared in The Ergonomics Report™ on 2010-01-11.